NATO’s senior leader on Tuesday rejected a Russian government proposal that would have required the European alliance to share details on a continentwide missile-defense system.

NATO Secretary-General Anders Fogh Rasmussen told Russia’s Interfax new agency in Brussels, a day before a summit to discuss the relationship between NATO and Russia, that Russia cannot be a direct participant in a planned missile-defense system.

Additionally, Mr. Rasmussen said: “The most promising path towards greater trust is more discussion, more political debate and exchange, rather than complicated legal formulas which would be difficult to agree on.”

Mr. Rasmussen said the planned missile-defense system is not aimed at countering Russia’s missiles, but rather at ensuring Europe’s security.

Russian President Dmitry Medvedev has proposed a treaty that would require NATO to provide Moscow with details on the numbers, types, deployment locations and top speeds of all missile interceptors and associated radar systems installed in the system, mainly to be built in Eastern Europe.

The Obama administration has proposed what it calls a “phased, adaptive approach” missile-defense shield designed to counter long-range missile threats. The system will develop in phases using both sea-based and ground-based interceptors. In the future, the system could be used to counter any intercontinental missiles fired at the United States from Iran.

Russia has opposed the missile defense, saying it is aimed at countering Moscow’s strategic missiles, a claim both the United States and NATO deny.

Poland and the Czech Republic plan to take part and Romania also announced it will participate in the system.

Dmitry Rogozin, a Russian official involved with the NATO missile-defense talks stated in an article in the New York Times on Tuesday that Russia opposes defenses that impinge on its sovereignty.

“Russia does not want U.S. anti-missile defenses to extend to our territory, especially to its North European part, because should a negative scenario develop, this could upset the strategic balance of forces between our country and the United States,” Mr. Rogozin wrote in an op-ed.

Many of NATO’s Eastern European members, who joined after the collapse of the Soviet Union, have supported the missile-defense system since it was first introduced by President George W. Bush.

Senior NATO leaders, including U.S. Defense Secretary Robert M. Gates, are gathered in Brussels for the NATO summit set to begin Wednesday. The summit is a follow-on meeting to last year’s summit in Lisbon when Mr. Medvedev met with senior leaders of NATO and agreed to cooperate with NATO on missile defense.